ABC is a triangle. Forces $\overrightarrow{P}, \overrightarrow{Q}, \overrightarrow{R}$ acting along $IA, IB$ and $IC$ respectively are in equilibrium, where $I$ is the incentre of $\Delta ABC$. Then $\overrightarrow{P} : \overrightarrow{Q} : \overrightarrow{R}$ is :

Question

( A ) $\cos A : \cos B : \cos C$
( B ) $\sin A : \sin B : \sin C$
( C ) $\sin \frac{A}{2} : \sin \frac{B}{2} : \sin \frac{C}{2}$
( D ) $\cos \frac{A}{2} : \cos \frac{B}{2} : \cos \frac{C}{2}$